Optical detection of electron-depletion region surrounding metal electrode on a dilute two-dimensional electron gas

Microscopic photoluminescence images were measured on a dilute two-dimensional electron gas (2DEG) in an n-type modulation doped quantum well at 5K. We observed electron-depletion regions surrounding metal electrodes formed by annealing of soldered indium or evaporated AuGeNi. The difficulty of forming an ohmic contact to a dilute 2DEG was probably due to the depletion region separating the 2DEG from the metal electrode.